This example shows how to work with web driver instances that were created at suite level

SuiteLevelWebdriverSample

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.ISuite;
import org.testng.ISuiteListener;
import org.testng.Reporter;
import org.testng.annotations.Listeners;
import org.testng.annotations.Test;

import java.util.HashMap;
import java.util.Map;

@Listeners (SuiteLevelWebdriverSample.CustomSuiteListener.class)
public class SuiteLevelWebdriverSample {
    @Test
    public void testMethod() {
        String currentSuiteName = Reporter.getCurrentTestResult().getTestContext().getSuite().getName();
        WebDriver driver = CustomSuiteListener.getDriver(currentSuiteName);
        if (driver == null) {
            throw new IllegalStateException("Webdriver instantiation failed.");
        }
        driver.get("http://www.facebook.com");
    }

    public static class CustomSuiteListener implements ISuiteListener {

        public static Map<String, WebDriver> webdriverMap = new HashMap<>();

        public static WebDriver getDriver(String suiteName) {
            return webdriverMap.get(suiteName);
        }

        @Override
        public void onStart(ISuite suite) {
            String suiteName = suite.getName();
            webdriverMap.put(suiteName, new FirefoxDriver());
        }

        @Override
        public void onFinish(ISuite suite) {
            String suiteName = suite.getName();
            WebDriver driver = getDriver(suiteName);
            if (driver != null) {
                driver.quit();
            }
        }
    }
}